Portable electric heaters must presently be limited to an electrical capacity of 1500 watts. This limit for continuous operation is set to reduce the risk of fire associated with continuous use heating devices operating at capacities beyond this power rating. This limit is also enforced by product certification laboratories such as Underwriters Laboratories.
However, in an enclosed space to be heated, the operation of a heater at 1500 watts or less results in extended heating times. Therefore, there is a need for an electric heater which operates at a higher power rating during the initial heating cycle when the space is at its coldest and then operates at a lower power rating for the remaining continuous heating operation.